The present invention relates to an improved device for administration of pellet medicaments into the subcutaneous tissue of a mammal, and in particular to a hand-held preloaded pellet implant device capable of sequentially implanting multiple pellets into the tissue.
Subcutaneous insertion is one method of administration of solid medicaments into a patient. The medical use of subcutaneous implants has been successfully utilized in certain treatments where it is desirable to maintain within the body a slow, constant release and absorption of a drug over an extended period of time. Delivery of hormone treatments by medical implants has proven medically successful and economically advantageous over other drug administration methods. It has been found that other forms of pharmaceutical administration such as oral and parenteral administration cause a drug to dissipate rapidly by absorption into body tissues, and thereby require a patient to undergo repeated administration. Frequent administrations of a drug treatment can be both expensive and, in the case of parenteral administrations, sometimes quite painful. On the other hand, subcutaneous drug implants, where practicable, obviate the need for frequent administrations and thus solve the problems of expense and discomfort.
Prior art implant delivery devices, however, have not proven successful. Several prior art devices, such as the one disclosed in U.S. Pat. No. 5,522,797, teach the use of a pellet injector gun which operates by the use of a spring or other biasing mechanism. These prior art devices are commonly used by veterinary practitioners on animals. Additionally, there are prior art devices that disclose a hand-held, manual pellet injector, but these also suffer from several major defects. For example, the devices disclosed in U.S. Pat. Nos. 3,921,632 and 4,994,028, allow the pellets to be loaded in the implanting device only after the device has been inserted into the subcutaneous tissue. The design of these prior art devices make the pellets prone to being dropped, thereby causing the medicaments to lose sterility. Further, these devices allow only one pellet to be inserted at a time and are not easily manipulable even in single pellet loading. Moreover, these implanting devices depend on gravity to keep the pellets within the implanting devices prior to actual placement within a patient.
The implant device of the present invention constitutes a vast improvement over the prior art devices. Use of the present implanting device obviates the need to load the pellets after the placement of the implanting device because the pellets may be pre-loaded in a plurality of laterally extending loading chambers. Also, the presence of xe2x80x98Oxe2x80x99 rings within the loading chambers and stoppers at the top of the loading chambers prevent the pellets from falling out and thus preserve pellet sterility. Moreover, a slidably movable plunger in a disposed central hollow chamber locks after being fully retracted thereby preventing reuse and possible blood contamination.
It is therefore an object of the present invention to provide a pellet implanting device having a plurality of pellet loading chambers.
It is also an object of the present invention to provide a pellet implanting device into which a plurality of pellets may be pre-loaded prior to incising a patient.
It is a further object of the present invention to provide a pellet implanting device that is capable of inserting a plurality of pellets at one incision.
It is yet another object of the present invention to provide a disposable pellet implanting device that is adapted for a single use.
It is still another object of the present invention to provide a pellet implanting device wherein pellets are held securely within the loading chambers.
These and other objects of the present invention will become increasingly more clear upon reading the following detailed description of the preferred embodiments in conjunction with the accompanying drawings.
According to the present invention, there is provided a device for the subcutaneous implanting of a pellet medicament into a mammal. The device includes a hollow central chamber through which a plunger assembly is slidably movable. The plunger assembly comprises a large head end in coaxial alignment with a stylet end. The stylet end of the plunger assembly is adapted to create a subcutaneous channel when inserted into and subsequently retracted from under the skin of a patient. In addition to being capable of forming a subcutaneous channel, the sides of the stylet end of the plunger are concave and slanted and therefore adapted to guide the pellets through the central chamber and into the subcutaneous channel after the stylet has been retracted into the central chamber. The interior of the central chamber further includes an automatic locking mechanism to lock the stylet end of the plunger assembly within the central chamber to prevent reuse.
Extending diagonally from the central chamber are a plurality of loading chambers into which medicinal pellets are pre-loaded. A finger hold is disposed proximate to a top end of the central chamber for single-handed hand use of the implant device. The interior of the loading chambers are in communication with the interior of the central chamber, but pellets are retained in the loading chambers by a plurality of xe2x80x98Oxe2x80x99 rings disposed at the ends of the interior of the loading chambers. A manually insertable flexible prod is then utilized to push the pellets through the xe2x80x98Oxe2x80x99 rings, then the central chamber, and then into one of the subcutaneous channels.